MESOSCALE PRECIPITATION DISCUSSION 0090
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
908 PM EDT FRI MAR 18 2016
 
AREAS AFFECTED...CENTRAL/SOUTHERN LA...SOUTHERN MS...FAR SOUTHERN
AL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 190100Z - 190600Z
 
SUMMARY...NUMEROUS HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGH THE EVENING HOURS. INTENSE RAINFALL RATES ALONG WITH
RELATIVELY SLOW CELL MOTION WILL FOSTER SOME FLASH FLOOD POTENTIAL
OVER THE NEXT FEW HOURS.

DISCUSSION...COLD-TOPPED CONVECTION WILL CONTINUE TO IMPACT
PORTIONS OF CENTRAL/SOUTHERN LA AND INTO SOUTHERN MS OVER THE NEXT
FEW HOURS AS MOIST AND UNSTABLE LOW LEVEL FLOW CONTINUES TO FEED
NORTH INTO A QUASI-STATIONARY FRONTAL ZONE ALONG WITH MULTIPLE
CLUSTERS OF ONGOING CONVECTION.

PWATS HAVE RISEN GENERALLY TO AROUND 1.5 INCHES...AND INSTABILITY
OVER SOUTHERN LA IS CHARACTERIZED BY MLCAPES OF 1000 TO 2000 J/KG
COURTESY OF STRONGER AFTERNOON SOLAR INSOLATION. THE LAST COUPLE
OF RUNS OF THE RAP SUGGESTS SOUTHWESTERLY 850 MB FLOW OF 20 TO 30
KTS PERSISTING THROUGH 06Z...WHICH GIVEN INSTABILITY STILL POOLED
OFFSHORE OVER THE WESTERN GULF OF MEXICO MAY TEND TO AT LEAST
SUSTAIN THE ONGOING AND EXPANDING ACTIVITY OVER SOUTHERN LA.

RAINFALL RATES OF UP TO 2 INCHES/HR WILL BE POSSIBLE...AND WITH
FAIRLY SLOW CELL MOTION AND SOME CONCERN FOR CELL-MERGERS AND
BACKBUILDING...THERE COULD LOCALLY BE SOME 3 TO 5 INCH TOTALS
THROUGH 06Z. THESE RAINFALL AMOUNTS MAY RESULT IN SOME RUNOFF
CONCERNS AND POSSIBLE FLASH FLOODING.

HIRES MODEL OUTPUT HAS NOT EXACTLY BEEN HANDLING THE ONGOING
ACTIVITY TOO WELL AND ONLY THE HRRR APPEARS TO HAVE A RELATIVELY
DECENT HISTORY OF DETAILING THE CONVECTIVE EVOLUTION OVER MS/LA.
WILL CONTINUE TO MONITOR AREAS OF ESPECIALLY SOUTHEAST LA AS THERE
HAVE BEEN SOME STRONGER SIGNALS FOR CONVECTION REDEVELOPING AND
FOCUSING OVER THIS AREA LATER IN THE NIGHT.

ORRISON

ATTN...WFO...JAN...LCH...LIX...MOB...

ATTN...RFC...LMRFC...SERFC...

LAT...LON   31848988 31838875 31448789 30468788 30128921 
            29358979 29189049 29369163 29619248 29979330 
            30399333 30979283 31529142